Quick power control (QPC) is a brand-new user equipment technology, aims at reducing power consumption of a user equipment, and rapidly controls an uplink power amplifier (PA) of the user equipment. According to this technology, after the user equipment (UE) completes sending a signal, the uplink power amplifier is rapidly turned off, and when there is a signal to be sent, the uplink power amplifier is started, thereby ensuring normal sending of a user signal, and saving the power consumption of the user equipment.
In a code division multiple access (CDMA) system, in order to keep constant transmit power, the user equipment adopts a cascading manner of a variable gain amplifier and a fixed gain amplifier to control the variable gain amplifier through an automatic gain control (AGC) technology, and adopts a manner of closed-loop power control to ensure that output power stably meets a requirement.
In a current QPC application, after the UE sends the signal, the UE turns off the uplink PA. However, due to a closed-loop negative feedback function of the AGC, the UE still increases, through the AGC, a gain on transmit power of the UE by the uplink PA, until the transmit power of the UE is increased to maximum transmit power. In this way, before the UE sends a signal again, the UE restarts the PA. In this case, the PA is started at a full gain, so that when the UE sends the signal, the UE sends the signal at the maximum transmit power, which causes a waste of the transmit power of the UE.